Preparation / Directions:
Makes two 9-inch loaves
In a large bowl let the yeast dissolve in the warm water.
Stir the potato water into the yeast. Whip the potatoes with the butter and the salt and beat into yeast. Stir in the whole wheat flour and 6 cups of the white flour. Beat 100 strokes. Cover with plastic wrap and refrigerate overnight.
Turn the dough out onto a very well-floured working surface. Punch down, then scrape up and knead, liberally flouring your hands and the surface as necessary. The dough will be very sticky and will absorb 2-3 cups more flour as you knead it. Add caraway seeds, if desired. When bouncy and relatively smooth - after about 10 minutes of kneading - divide in half and form 2 large loaves. Place in greased 9-inch bread pans, cover lightly with a towel, and let rise until the dough swells slightly over the tops of the pans.
Bake in a preheated 350 F oven for 1 hour and 10 minutes. Rub the tops of the loaves with butter while still warm. Turn out onto racks to cool.